1. Field of the Invention
The present invention is generally related to a method for forming a bio-mimicking scaffold, and more particularly to a method for forming a porous bio-mimicking scaffold.
2. Description of the Prior Art
Electrospinning is one of techniques to produce nanofibers. The principle of electrospinning is to utilize a material solution under high voltage. When the charge repulsion force generated by the charges accumulated on the surface of the solution is larger than the surface tension, a Taylor cone is formed on the surface of the solution. The cone tip exceeds the tension to emit nanofibers toward a collecting plate with an opposite electric property. Different collecting plates can be used to collect nanofibers in different directions.
Generally, the diameter of nanofibers is about 0.01 times the diameter of common fibers. In one gram of fibers with a diameter of 50 nm, the total surface area is about 1,000 m2. Since nanofibers have tremendous surface area and high porosity, they have many special applications. Traditionally, the material of nanofibers is carbon fibrils, man-made polymeric fiber, or alumina fiber, etc.
Electrospinning nanofibers having high strength and high surface area can be utilized to fabricate cloth with special functions, such as chemical resistant, water-proof and breathable, anti-staining, and so forth. In textile industry, nanofibers have great market. Nano-Tex Co. has developed and commercialized products made of nanofibers. Nanofibers are also considered as scaffolds for filtration and medical tissue engineering. In addition, they have potential in the applications of transporting media for medicine, sensors, nano-electronics, etc.
Besides, in the biotechnology application of nanofibers, there are reports in discussing the interaction between nanofibers and cells. Elias et al implant human osteoblasts into scaffolds comprised by nanofibers with different dimensions to perform culture in vitro. After performing culture for 3 weeks, cell growth is in a good condition and alkaline phosphatase activity and calcium concentration secreted by the osteoblasts are increased with the increase of the culture time.
Yoshimoto et al implant mesenchymal stem cells into scaffolds comprised by poly caprolactone (PCl) nanofibers to perform culture by a dynamic bio-reactor. After performing culture for 4 weeks, it is found that not only cell-polymer constructs maintain the original dimension and shape but also cell laminated proliferation and the growth of cell matrix for the cells in the constructs are observed by SEM. In addition, it is found from the immunohistochemical staining method that type I collagen is formed. Therefore, in light of the above results, it shows that nanofibers can aid cell growth.
However, if nanofibers are piled up tightly and have low porosity, cell growth and differentiation will be affected. Christopher et al have found that cow endothelial cells grow on bio-matrix with a small pore diameter (<100 μm) and have higher apoptosis probability. Thus, a novel method for preparing a porous bio-mimicking scaffold is needed to provide a bio-mimicking scaffold with a proper pore diameter and appropriate porosity.